The Walls of Dubrovnik () are a series of defensive stone walls that have surrounded and protected the citizens of the afterward proclaimed maritime city-state of Dubrovnik (Ragusa), situated in southern Croatia, since the city's founding prior to the 7th century as a Byzantium castrum on a rocky island named Laus (Ragusia or Lave). With numerous additions and modifications throughout their history, they have been considered to be amongst the great fortification systems of the Middle Ages, as they were never breached by a hostile army during this time period. In 1979, the old city of Dubrovnik, which includes a substantial portion of the old walls of Dubrovnik, joined the UNESCO list of World Heritage Sites.